Oral care compositions comprising peroxide sources are useful for cleaning and whitening teeth. The peroxide may be present as hydrogen peroxide, or as a source of bound hydrogen peroxide. Sources of bound hydrogen peroxide include polyvinylpyrrolidone (PVP)-H2O2 complexes, urea peroxide, calcium peroxide and sodium percarbonate. The peroxide can bleach teeth, remove stains, and kill cariogenic bacteria. However, peroxide compounds are highly reactive with common ingredients found in oral care formulations. Moreover, hydrogen peroxide can spontaneously decompose to form oxygen gas and water, so that on storage, the composition containers may bloat, burst or leak. Consequently, the remaining formulation will have a reduced whitening and cleaning efficacy. Some formulations initially comprise very high levels of peroxide, which decomposes over time, so that the exact amount of peroxide delivered on application is variable and largely dependent on how long and under what conditions the formulation has been stored.
There is therefore a need for improved peroxide-containing oral care compositions which exhibit improved stability of the peroxide, and which are therefore suitable for long-term storage without a significant loss of whitening and cleaning efficacy.